In South Indian music composed pieces are mainly set for the voice and have lyrics: the compositions can largely be attributed to three composers who lived from the mid 1700s to the early 1800s, Tyagaraja, Muthuswami Dikshitar, and Syama Sastri. Their compositions are called krti, and these are devotional songs. In North Indian classical music, the most common form of singing is called khyal, a word which means imagination; however, the khyal is thought to have gained ascendancy only in relatively recent times, having superseded the dhrupad form of singing. Dhrupad means “fixed words”. Another popular vocal form of North Indian classical music is the thumri, which derives its text, as do the bhajans, from devotional literature, and more particularly the theme of Radha and Krishna. In North Indian classical music, instrumental as well as vocal, the musicians are described as being affiliated with gharanas (literally, houses) or particular styles of music. Among the well-known gharanas are the “Kirana” gharana, whose most notable exponent was Baba Allauddin Khan and the Gwalior Gharana, immortalized by Pandit Vishnu Digambar Paluskar, whose name is more generally associated with the revival of North Indian culture; just as well-known are the Agra, Atrauli-Jaipur, and numerous other gharanas.